kubernets：Helm小练手

简述

helm是k8s的包管理工具，类似于我们手机上的华为市场或者小米的应用商店。他提供了包的查找，安装，卸载，状态查看一条龙的服务。最近学了一下，自己想了个例子，练练手

例子涵盖的技能点

• 从文件中读取内容
• Hook
• 变量的定义，使用
• NOTES.txt
• 流程控制操作符的应用

开始操练起来

• 创建一个chart

helm create nginx-base-package

• 删除多余的文件

rm -rf  templates/*

• 编写变量文件values.yaml

deploymentLabel:
   app: nginx
   type: middleware
   environment: test

deploymentSpec:
   replicas: !!int "1"
   
deploymentTemplate:
   image: nginx
   ports:
     containerPort: !!int "80"
   env:
     shell: bash
     author: hananmin

• 创建两个文件用于存储configmap

#deployment-configmap-02.toml
action = "The config of deployment 02"

#deployment-configmap.toml
action = "The config of deployment"
remark = "The remark of deployment"

• 创建configmap的模板

#templates/configmap.yaml 
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Release.Name }}-{{ .Release.Revision }}-configmap
data:
  {{- $file := .Files }}
  {{- range list "deployment-configmap.toml"}}
  {{ . }}: |-
     {{  $file.Get .|quote }}
  {{- end }}
  {{- (.Files.Glob "deployment-configmap-02.toml").AsConfig | nindent 2 }}

• 创建deployment的模板

#templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-{{ .Release.Revision }}-deployment
  labels:
    {{- range $key, $val :=  .Values.deploymentLabel }}
       {{ $key }}: {{ $val | quote }}
    {{- end}}
spec:
  replicas: {{ .Values.deploymentSpec.replicas }}
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
       - name: nginx
         image: nginx:1.7.9
         env:
           {{- range $key, $val :=  .Values.deploymentLabel }}
              - name: {{ $key }}
                value: {{ $val | title|quote }}
           {{- end}}
         ports:
           - containerPort: {{ .Values.deploymentTemplate.ports.containerPort }}
         volumeMounts:
           - name: config-volume
             mountPath: /tmp/config
      volumes:
       - name: config-volume
         configMap:
           name: {{ .Release.Name }}-{{ .Release.Revision }}-configmap

• 创建Hook的模板

#templates/pre-install.yaml
apiVersion: batch/v1
kind: Job
metadata:
  name: "{{ .Release.Name }}"
  labels:
    helm.sh/chart: "{{ .Release.Name }}-{{ .Chart.Version }}"
  annotations:
    # This is what defines this resource as a hook. Without this line, the
    # job is considered part of the release.
    "helm.sh/hook": pre-install
    "helm.sh/hook-weight": "5"
    "helm.sh/hook-delete-policy": before-hook-creation  
spec:
  template:
    metadata:
      name: "{{ .Release.Name }}"
      helm.sh/chart: "{{ .Release.Name }}-{{ .Chart.Version }}"
    spec:
      restartPolicy: Never
      containers:
      - name: pre-install-job
        image: "busybox:latest"
        command: ["echo","I am pre-install Job,time:","`date`"]

• 创建NOTE.TXT

# templates/NOTES.txt
Thank you for installing {{ .Chart.Name }}.

Your release is named {{ .Release.Name }}.

To learn more about the release, try:

  $ helm status {{ .Release.Name }}
  $ helm get {{ .Release.Name }}

• 检查一下

 helm install --dry-run --debug

运行完命令你会看到，给k8s的MANIFEST，如果输出中没有报错，可以进行下面的操作

• 安装

 helm install nginx-base-package/

helm install命令不会等待所有的pod都启动，后续查看release的状态，需要用到helm status

在k8s层面检查一下

• 首先，我们的pre-install启动了一个job
  
• 其次，应该有一副本的deployment启动
  
• 因为deployment是一副本，所以应该有一个pod启动
  

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